Means fob rehabilitating used carbon pakeb



June 13, 1933. L. H. ELKAN 1,913,704

MEANS FOR REHABILITATING USED CARBON PAPER Filed May 29, 1931 l 1 6 76 II Patented June 13, 1933 UNITED STATES LEO H. ELKAN, OF CHICAGO,ILLINOIS MEANS FOR BEHABILITATING USED CARBON PAPER Application filedMay 29, 1931. Serial No. 540,924.

The invention relates to carbon paper and more particularly it relatesto a novel method of treating carbon paper to prolong its service life.

. One of the objects of the invention is the provision of a novel methodof treatment of used or pitted sheets of carbon paper to rehabilitatethe same.

A more particular object is the provision of a novel method of treatmentof sheets of carbon. paper which, by reason of repeated use have becomeincapable of producing satisfactory copies of an original manuscript.

Another object of the invention is the provision of a novel device forpracticing the above mentioned method whereby used sheets of carbonpaper of the kind ordi 'narily used in typewriting are adapted for 20forming satisfactory copies in substantially the same number as were thesheets when used for the first time.

A further and more general object is the provision of a novel method oftreating used sheets of paper which have a coating of fusible material,a portion of which is lost by each successive use, whereby the servicelife of such sheets may be prolonged several times and substantialsavings effected by reducing the number of sheets required and theoriginal outlay for same.

Other further and more particular ob jects will become apparent as thespecification proceeds.

It is well known to those familiar with the art that so-called carbonpapers consist of specially treated sheets of tissue paper having acoating of ink on one face of a consistency that will neither smear norspread.

The ink used for such coatings generally comprises a mixture ofwax,'color and oil in proportions to produce the desired results as toconsistency and other qualities including a low fusing point. As is wellknown, pressure on the uncoated side of the sheet causes the ink to betransferred to a paper sheet laid against the coated 'side and theimpact of the typewriter keys 50 against the original sheet causes theunderlying sheet or sheets of carbon paper to become pitted by losingink on corresponding underlying small areas or spots. The pits or spotson the sheet which is thus deprived of its ink increase in number andsize with each successive use of the sheet and upon continued use therewill be an ever increasing number of instances in which the typewriterkeys strike wholly or partially over the pits or spots which 'are barrenof ink and as a result faint or otherwise unsatisfactory impressions ofthe type are imposed on the copies. For this reason carbon sheets arefrequently discarded after they have been used a relatively few times.The sheets thus discarded still retain a large proportion of the coatingof ink or so-called carbon material and entails a substantial waste, theavoidance of which is another object of the invention.

The invention contemplates multiplying the service life of the carbonsheets several times and saving a substantial portion of the coatingmaterial hitherto discarded. These results are accomplished by heatingthe sheet until the coating material is fused and is caused to flow andspread uniformly to fill the pits. While the fusion may be accomplishedby applying the heat'to either side of the sheet I preferably apply itto the back or uncoated side of the sheet by pressing the sheets againsta heated surface and imparting a reciprocatory movement thereto. As aresult of the fusing process that follows the coating will again be of auniform thickness only slightly less than the thickness of thecoatinginaterial at the time the sheet was initially used. The fusingprocess by means of which the rehabilitation of the sheet isaccomplished ma be repeated several times, the thickness 0 the coatingin each case being only slightly diminished and as a result the servicelife of the sheets is in many cases multiplied or increased severaltimes over that of the same sheets if untreated.

Satisfactory results are obtained in practice by using a limited amountof pressure in applying the back or uncoated side of the sheet to asurface heated to a temperature above the fusing point of the coatingmaterial.

Referring now to the drawing which illustrates one embodiment of adevice by means of which the method may be practiced,

Fig. 1 is a plan view of the device;

Fig. 2 is a side elevational view of the device shown in plan in Fig. 1drawn to a smaller scale;

Fig. 3 is a plan view showing the device with the top cover removed anddrawn to a larger scale;

Fig. 4 is a sectional View along the line 44 of Fig. 3; and

Fig. 5 is a sectional view of the device taken along the line 5-5 ofFig. 3 drawn to a smaller scale.

Referring now more particularly to the drawing, I have shown oneembodiment of a heating device, suitable for practicing the method,which is generally designated by the numeral 10. The heatin device 10comprises a housing 11 detaliably mounted upon a table or desk 13 bymeans of a supporting arm 12. The heating device may be shifted asdesired from one table or des to another and clamped into position bymeans of a screw 14.

The housing provides an enclosure for a plurality of resistance coils 15arranged in any desired manner. A conduit 18 containing conductors l9and 20 connects the coils 15 with a source of electrical energy notshown. The free end of the conduit 18 is preferably provided with a plugfor insertion in a wall socket to enable the device to be set up for useat any convenient point in a room equipped with plugs. While I haveshown the device as heated by resistance coils it is obvious that it maybe used in the practice of the method by utilizing any other source ofheat energy. Operation of the device may be started b plugging In anyconvenient socket and is stopped by simply removing the plug from thesocket. The thermostatic switch 21 is shown diagrammatically and may beany type of switch to automatically break the circuit when thetemperature reaches a predetermined point considered as a desirablemaximum.

The coils 15 rest upon sheets 16 of asbestos or other non-conductingmaterial and are held in parallel longitudinal rows by clips 22. Thesheets 16 rest upon a plate member 23 forming the bottom of the housing.The bottom plate 23 rests upon the supporting arm 12 and is fastenedthereto by any suitable means such as welding or by screw bolts, notshown.

The top of the housing 11 comprises an outwardly convex or cylindricalshaped covor 24 having its longitudinal edges turned inwardly to formflanges 28. The inturned flanges 28 slidably engage the edges of thebottom plate 23 to form a guide which permits the cover 24 to be removedfrom the housing for inspection or the renewal of parts. The cover 24 ispreferably given a slight curvature. The slightly convex curvature ofthe cover 24 enables a substantial portion of the sheet 16 to be appliedthereto under pressure by holding the ends of the sheet with the hands.The curvature of the cover being flat the movement of the sheet isaccomplished with a sweep or a stroke which is easy to accomplish andcontrol. A further advantage of the flat curvature of the cover 24 isthat all parts of the same are in close proximity to the heating coils15. The close spacing of the cover 24 to the coils 15 permits the coverto be quickly heated to the necessary temperature to fuse coatingmaterial on the carbon sheets and minimizes the waste of energy whichwould otherwise result.

The method of the invention is practiced by first connecting the devicewith any suitable source of energy and raising the temperature of thecover 24 to a point where the coatin of material on a sheet 28 will befused i brought into close contact therewith as shown in Fig. 5. Theelements of the cylindrical cover 24 are preferably but not necessarilyhorizontal and the operator manipulates the sheet of carbon paper 29 bybringing the uncoated side of the sheet into pressure contact with thecover 24. That portion of the sheet being heated will be heldsubstantially horizontal and the sheet is manipulated by moving iteither longitudinally or transversely ,or in both directions over thecover 24. The sheet will be so manipulated as to uniformly fuse thecoating over a considerable portion of its area. As a result the liquidor semi-liquid coating will be caused to flow and fill the pits or barespots. The fused coating material hardens as soon as the sheet isremoved from proximity to the device and upon cooling a coating ofuniform thickness results.

The dimensions of the device are preferably such that a sheet of carbonpaper of the usual size and width may be moved 1eciprocally in eitherdirection to get the desired uniformity of fusing and thickness ofcoating. A flange 27 on one end of the cover 24 serves as a guide toassist in keeping the sheet 29 in proper position over or on the heatedcover.

The manipulation of the sheet 29 to produce proper fusion over areassufficiently large to get the best results makes it desirable that thecover be convex outwardly as shown. The particular de ree of convexityor curvature may be varie to suit the individual requirements of theinstallation.

The device is simple and economical in construction and may be operatedby unskilled persons. The ability to manipulate the sheet to practicethe method and to rehabilitate the sheet to fill pits contained thereinis soon acquired by any of the members of an oflice .force and enablessubstantial savings to be effected in the outlay for carbon paper byutilizing slack periods for the rehabilitation of used paper.

Having thus described my invention, it is obvious that variousimmaterial modifications may be made in the same Without departing fromthe spirit of my invention; hence, I do not Wish to be understood aslimiting myself to the exact form, construction, arrangement andcombination of parts herein shown and described or mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. In a device of the kind described, a closed housing comprising a flatbottom plate, a slightly curved plate forming the top and side walls ofthe housing and end plates fastened to the bottom plate, said end plateshaving their top portions conforming to the inner periphery of thecurved plate and terminating in closely spaced relation thereto, avertically projecting flange member bounding one edge of the curvedplate, the ends of said curved plate having inturned edge portions inslidable engagement with the lower face of the bottom plate, saidinturned edge portions adapting the curved plate for easy mounting uponand removal .from the housing.

2. In a device of the kind described, a closed housing comprising a flatbottom plate, a slightly curved plate forming the top and side walls ofthe housing and end plates fastened to the bottom plate, said end plateshaving their top portions conforming to the inner periphery of thecurved plate and terminating in closely spaced relation thereto, avertically projecting flange member bounding one edge of the curvedplate, the ends of said curved plate having inturned edge portions inslidable engagement with the lower face of the bottom plate, saidinturned edge portions adapting the curved plate for easy mounting uponand removal from the housing, a resistance coil mounted in the housingin close proximity to said curved plate,

' a support for said housing, clamping means operable to fasten saidsupport to a table or desk, and conductors adapted to connect the coilwith a source of electrical energy.

In witness whereof, I hereunto subscribe my name this 25th day of Ma A.1)., 1931.

LEO ELKAN.

